1. Field of Invention
The invention relates to card-shaped electronic apparatuses, and more particularly, to contact type card-shaped electronic apparatuses that use a metal plate as its outer casing, including PC cards, such, as for example, IC memory cards, I/O cards and the like.
2. Description of Related Art
In recent years, facsimile modem expansion boards for communicating with an external apparatus such as a personal computer (hereinafter referred to as PC), hard discs for expansion, and the like have been reduced to a card size, and made available as PC cards, in addition to the already existing card-shaped electronic apparatuses, such as, for example, IC memory cards. These card-shaped electronic apparatuses use a metal plate such as a stainless steel plate (hereinafter referred to as SUS) as an outer casing to increase the rigidity of the card-shaped electronic apparatus, to provide electrostatic resistance and to eliminate noise problems. Hereafter, a PC card will be described as an example of a card-shaped electronic apparatus.
FIG. 13 is an exploded view of a conventional PC card, and FIG. 14 is a cross-sectional view thereof. The PC card according to this example is one in which a conventional PC expansion board or an accessory is implemented in a card-shaped apparatus. In the interior thereof, an input/output integrated circuit (hereinafter referred to as an input/output IC) 5, a semiconductor memory 6 and the like are mounted on a substrate 4. The PC card uses metal plates 2 as upper and lower outer casings for the card, as described above, in order to improve its transportability, handling capability and reliability. The metal plates 2 are fixed to a plastic frame 8 by a fixing means such as adhesive. In order to prevent unnecessary radiation, the upper and lower metal plates 2 are further connected to ground line (hereinafter referred to as GND) of the substrate 4 through a conductive spring 3, as shown in FIG. 14. The PC card is equipped with a connector 1 for mounting on a PC apparatus.
Further, in order to facilitate the inserting and withdrawing of the card, there have been cards in which independent slip-stoppers are attached to the metal plates 2, or slip-stopping grooves are provided on the plastic case 8 in the side sections of the card-shaped electronic apparatus.
Some of the conventional PC cards are provided with an electrostatic countermeasure that is effective upon mounting on a PC. On the other hand, some of the cards are not provided with such a countermeasure due to the limitations imposed by factors such as the space and cost of the card, and the structure of a PC, i.e., the PC""s receiving apparatus. In particular, even though a conventional electrostatic countermeasure may be provided with a card, the countermeasure in the card alone may not be sufficient, and a PC apparatus may be required to include a countermeasure according to the structure of the electrostatic countermeasure implemented in the card. Also, an electrostatic countermeasure may, in some cases, be implemented in a PC alone. For example, a lid is provided at the PC card insertion opening, and a piece of metal is provided adjacent to the lid so that static electricity is led out to the frame GND of the PC through the piece of metal when the lid is opened and closed. However, although a lid may be provided at a card insertion opening of a relatively large PC, it is difficult to provide such a structure in the latest PCs, such as, for example, notebook type PCs because of their size, depth and thickness.
Furthermore, PC cards are not provided with an electrostatic countermeasure while they are inserted in a PC. As a result, when a person charged with static electricity touches the card that is inserted in the PC, the charge (static electricity) of the person flows through the metal plates, the conductive spring and the GND within the card to the PC apparatus. As a result, this could become one of the situations that triggers malfunctions, such as, for example, erroneous operation and halt of the PC.
Therefore, it is an object of the present invention to provide a card-shaped electronic apparatus that is electrostatic-resistant and is capable of securely preventing discharge of static electricity by the card alone.
Also, it is an object of the present invention to provide a highly reliable card-shaped electronic apparatus which does not trigger malfunctions, such as, erroneous operation and halt of a PC and other apparatuses when connected thereto.
Furthermore, it is an object of the present invention to realize, in a card-shaped electronic apparatus, a structure which facilitates its operation when the card is inserted for mounting or withdrawn for dismounting.
The invention has been made in order to solve the above-described problems, and its content will be described below.
A card-shaped electronic apparatus in accordance with the invention comprises a substrate on which electronic devices are mounted, a terminal that is disposed on one side of the substrate and that is brought into contact with a data transmission and reception section of an external apparatus main body for electrical connection, a frame that is positioned at the periphery of the substrate, a metal member that is connected to the frame and covers the substrate at least at the side of the terminal to define an outer casing section, and an insulation member that is connected to the frame at an opposite side with respect to the side of the terminal of the frame. By providing such a structure, the outer casing is formed from an insulation member at the location on the opposite side of the location where the terminal is provided, so that an area of the insulation member is held for mounting or removing the card. Accordingly, for example, even when a person charged with static electricity inserts or withdraws the card, the static electricity is not discharged to the apparatus side, and as a result, malfunctions of the apparatus mounted therewith can be prevented. In addition, since the terminal side is covered by the metal member, radiation is restricted to thereby eliminate noise problems.
The metal member covers both sides of the substrate, and further includes a conductor member that electrically connects the metal member and the substrate. In other words, the metal member is connected to GND of the substrate. As a result, problems caused by external noise and the like can be securely prevented.
Furthermore, the insulation member is disposed at least at a location that protrudes from the external apparatus body when mounted on the external apparatus. By this, the area that is covered by the metal member increases. Accordingly, the rigidity of the card is readily maintained, and even when a person charged with static electricity touches the card that is inserted in the external apparatus, the static electricity is not discharged to the external apparatus side since the portion of the outer casing that protrudes from the external apparatus body is in the insulation condition, and therefore malfunctions of the external apparatus are prevented.
Also, the insulation member and the frame may be integrally formed, the metal member and the insulation member may be integrally formed, and the metal member, the insulation member and the frame may be integrally formed. By providing such structures, the number of parts and manufacturing steps can be reduced, and the cost can be reduced.
Also, the insulation member may be formed to be externally protruded and to have a U-shape cross-section. By forming the insulation member in a U-shape, the thickness of the insulation member whose rigidity is lower compared with the metal can be increased to increase the rigidity (strength) of the insulation member. A space for mounting electronic devices such as semiconductor memories and the like can also be provided in an area that is covered by the insulation member of the substrate, and therefore a large substrate can be used. Also, since the thickness becomes greater by forming it in a U-shape, the operability of the card upon its insertion and withdrawal is improved.
Also, a deform prevention section in a protruded shape may be formed in the interior of the insulation member. By providing the deform prevention section, the protruded deform prevention section contacts the substrate or the insulation member on the opposite side so that the insulation member is prevented from being deformed when the card is gripped and held. As a result, the thickness of the insulation member can be reduced. In particular, the deform prevention members formed on the respective insulation members which are disposed on both surfaces of the substrate may be made engageable with each other, so that the insulation members are prevented from being deformed, and mutual positioning thereof is readily performed.
Also, the metal member may be disposed to cover the entire surface of the substrate, and the insulation member may be disposed to cover the external surface of the metal member. The insulation member is disposed to cover the metal member which has a certain rigidity, so that the insulation member can be selected from a wider range of materials. The insulation member that covers the metal member can be formed into a sheet. When the insulation member is formed into a sheet, the insulation member can be substantially readily disposed at the external surface of the metal member.
Preferably, plastic material is used for the insulation member. By using a plastic material, a high insulation function is obtained, a light-weight member can be readily formed in any desired shape, and it can be formed into a sheet.
Also, in any one of the above-described structures, the insulation member is characterized in having a slip-stopper provided therewith. By providing such a structure, the operability of the card upon insertion and extraction of the card to a mounting body is improved.